// Copyright 2021 TiKV Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// NOTE: The code in this file is based on code from the
// TiDB project, licensed under the Apache License v 2.0
//
// https://github.com/pingcap/tidb/tree/cc5e161ac06827589c4966674597c137cc9e809c/store/tikv/commit.go
//

// Copyright 2020 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package transaction

import (
	"bytes"
	"encoding/hex"
	"time"

	"github.com/opentracing/opentracing-go"
	"github.com/pingcap/kvproto/pkg/kvrpcpb"
	"github.com/pkg/errors"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/tikv/client-go/v2/config/retry"
	tikverr "github.com/tikv/client-go/v2/error"
	"github.com/tikv/client-go/v2/internal/client"
	"github.com/tikv/client-go/v2/internal/locate"
	"github.com/tikv/client-go/v2/internal/logutil"
	"github.com/tikv/client-go/v2/metrics"
	"github.com/tikv/client-go/v2/tikvrpc"
	"go.uber.org/zap"
)

type actionCommit struct {
	retry      bool
	isInternal bool
}

var _ twoPhaseCommitAction = actionCommit{}

func (action actionCommit) String() string {
	return "commit"
}

func (action actionCommit) tiKVTxnRegionsNumHistogram() prometheus.Observer {
	if action.isInternal {
		return metrics.TxnRegionsNumHistogramCommitInternal
	}
	return metrics.TxnRegionsNumHistogramCommit
}

func (action actionCommit) handleSingleBatch(c *twoPhaseCommitter, bo *retry.Backoffer, batch batchMutations) error {
	keys := batch.mutations.GetKeys()
	req := tikvrpc.NewRequest(tikvrpc.CmdCommit, &kvrpcpb.CommitRequest{
		StartVersion:  c.startTS,
		Keys:          keys,
		CommitVersion: c.commitTS,
	}, kvrpcpb.Context{
		Priority:               c.priority,
		SyncLog:                c.syncLog,
		ResourceGroupTag:       c.resourceGroupTag,
		DiskFullOpt:            c.diskFullOpt,
		TxnSource:              c.txnSource,
		MaxExecutionDurationMs: uint64(client.MaxWriteExecutionTime.Milliseconds()),
		RequestSource:          c.txn.GetRequestSource(),
		ResourceControlContext: &kvrpcpb.ResourceControlContext{
			ResourceGroupName: c.resourceGroupName,
		},
	})
	if c.resourceGroupTag == nil && c.resourceGroupTagger != nil {
		c.resourceGroupTagger(req)
	}

	tBegin := time.Now()
	attempts := 0

	sender := locate.NewRegionRequestSender(c.store.GetRegionCache(), c.store.GetTiKVClient(), c.store.GetOracle())
	for {
		attempts++
		reqBegin := time.Now()
		if reqBegin.Sub(tBegin) > slowRequestThreshold {
			logutil.BgLogger().Warn("slow commit request", zap.Uint64("startTS", c.startTS), zap.Stringer("region", &batch.region), zap.Int("attempts", attempts))
			tBegin = time.Now()
		}

		resp, _, err := sender.SendReq(bo, req, batch.region, client.ReadTimeoutShort)
		// If we fail to receive response for the request that commits primary key, it will be undetermined whether this
		// transaction has been successfully committed.
		// Under this circumstance, we can not declare the commit is complete (may lead to data lost), nor can we throw
		// an error (may lead to the duplicated key error when upper level restarts the transaction). Currently the best
		// solution is to populate this error and let upper layer drop the connection to the corresponding mysql client.
		if batch.isPrimary && sender.GetRPCError() != nil && !c.isAsyncCommit() {
			c.setUndeterminedErr(errors.WithStack(sender.GetRPCError()))
		}

		// Unexpected error occurs, return it.
		if err != nil {
			return err
		}

		regionErr, err := resp.GetRegionError()
		if err != nil {
			return err
		}
		if regionErr != nil {
			// For other region error and the fake region error, backoff because
			// there's something wrong.
			// For the real EpochNotMatch error, don't backoff.
			if regionErr.GetEpochNotMatch() == nil || locate.IsFakeRegionError(regionErr) {
				err = bo.Backoff(retry.BoRegionMiss, errors.New(regionErr.String()))
				if err != nil {
					return err
				}
			}
			same, err := batch.relocate(bo, c.store.GetRegionCache())
			if err != nil {
				return err
			}
			if same {
				continue
			}
			return c.doActionOnMutations(bo, actionCommit{true, action.isInternal}, batch.mutations)
		}

		if resp.Resp == nil {
			return errors.WithStack(tikverr.ErrBodyMissing)
		}
		commitResp := resp.Resp.(*kvrpcpb.CommitResponse)
		// Here we can make sure tikv has processed the commit primary key request. So
		// we can clean undetermined error.
		if batch.isPrimary && !c.isAsyncCommit() {
			c.setUndeterminedErr(nil)
			reqDuration := time.Since(reqBegin)
			c.getDetail().MergeCommitReqDetails(reqDuration, batch.region.GetID(), sender.GetStoreAddr(), commitResp.ExecDetailsV2)
		}
		if keyErr := commitResp.GetError(); keyErr != nil {
			if rejected := keyErr.GetCommitTsExpired(); rejected != nil {
				logutil.Logger(bo.GetCtx()).Info("2PC commitTS rejected by TiKV, retry with a newer commitTS",
					zap.Uint64("txnStartTS", c.startTS),
					zap.Stringer("info", logutil.Hex(rejected)),
				)

				if !batch.isPrimary || !bytes.Equal(rejected.Key, c.primary()) {
					logutil.Logger(bo.GetCtx()).Error("2PC commitTS rejected by TiKV, but the key is not the primary key",
						zap.Uint64("txnStartTS", c.startTS),
						zap.String("key", hex.EncodeToString(rejected.Key)),
						zap.String("primary", hex.EncodeToString(c.primary())),
						zap.Bool("batchIsPrimary", batch.isPrimary))
					return errors.New("2PC commitTS rejected by TiKV, but the key is not the primary key")
				}

				// Do not retry for a txn which has a too large MinCommitTs
				// 3600000 << 18 = 943718400000
				if rejected.MinCommitTs-rejected.AttemptedCommitTs > 943718400000 {
					return errors.Errorf("2PC MinCommitTS is too large, we got MinCommitTS: %d, and AttemptedCommitTS: %d",
						rejected.MinCommitTs, rejected.AttemptedCommitTs)
				}

				// Update commit ts and retry.
				commitTS, err := c.store.GetTimestampWithRetry(bo, c.txn.GetScope())
				if err != nil {
					logutil.Logger(bo.GetCtx()).Warn("2PC get commitTS failed",
						zap.Error(err),
						zap.Uint64("txnStartTS", c.startTS))
					return err
				}

				c.mu.Lock()
				c.commitTS = commitTS
				c.mu.Unlock()
				// Update the commitTS of the request and retry.
				req.Commit().CommitVersion = commitTS
				continue
			}

			c.mu.RLock()
			defer c.mu.RUnlock()
			err = tikverr.ExtractKeyErr(keyErr)
			if c.mu.committed {
				// No secondary key could be rolled back after it's primary key is committed.
				// There must be a serious bug somewhere.
				hexBatchKeys := func(keys [][]byte) []string {
					var res []string
					for _, k := range keys {
						res = append(res, hex.EncodeToString(k))
					}
					return res
				}
				logutil.Logger(bo.GetCtx()).Error("2PC failed commit key after primary key committed",
					zap.Error(err),
					zap.Uint64("txnStartTS", c.startTS),
					zap.Uint64("commitTS", c.commitTS),
					zap.Strings("keys", hexBatchKeys(keys)))
				return err
			}
			// The transaction maybe rolled back by concurrent transactions.
			logutil.Logger(bo.GetCtx()).Debug("2PC failed commit primary key",
				zap.Error(err),
				zap.Uint64("txnStartTS", c.startTS))
			return err
		}
		break
	}

	c.mu.Lock()
	defer c.mu.Unlock()
	// Group that contains primary key is always the first.
	// We mark transaction's status committed when we receive the first success response.
	c.mu.committed = true
	return nil
}

func (c *twoPhaseCommitter) commitMutations(bo *retry.Backoffer, mutations CommitterMutations) error {
	if span := opentracing.SpanFromContext(bo.GetCtx()); span != nil && span.Tracer() != nil {
		span1 := span.Tracer().StartSpan("twoPhaseCommitter.commitMutations", opentracing.ChildOf(span.Context()))
		defer span1.Finish()
		bo.SetCtx(opentracing.ContextWithSpan(bo.GetCtx(), span1))
	}

	return c.doActionOnMutations(bo, actionCommit{isInternal: c.txn.isInternal()}, mutations)
}
